Using an interface device, a user can interact with a computer system to perform functions and tasks on the computer, such as playing a game, experiencing a simulation or virtual reality environment, performing computer aided design, operating a graphical user interface (GUI), or otherwise influencing events or images displayed on the screen. Common human-computer interface devices used for such interaction include a joystick, mouse, trackball, steering wheel, stylus, tablet, pressure-sensitive ball, or the like, that is connected to the computer system controlling the displayed environment.
In some interface devices, force feedback or tactile feedback is also provided to the user, also known more generally herein as “haptic feedback.” These types of interface devices can provide physical sensations that are felt by a user using the controller or manipulating the interface device. One or more actuators may be used in the device and may be connected to the controlling computer system. The computer system controls forces on the haptic feedback device, typically in conjunction with displayed events and interactions on the host by sending control signals or commands to the haptic feedback device and the actuators. One example of an interface device providing haptic feedback is a computer mouse having an actuator and providing haptic effects corresponding to graphical events displayed on a computer screen, such as an explosion in a video game.
With some interface devices, a user interacts with a graphical environment displayed by a computer system through contact with a touch-sensitive device, such as a touchpad or a touch screen. For example, laptop computers are often equipped with a touchpad that allows users to control a graphical object, such as a cursor or pointer, by placing a finger on the touchpad and moving the finger along the surface of the touchpad in a chosen direction. Recently, touch-sensitive computer mice have been developed that allow a user to interact with a graphical environment by simultaneously moving the mouse and performing touch gestures on a surface of the mouse, such as Apple Inc.'s Magic Mouse. While some touch-sensitive input devices only accurately recognize and capture a single touch contact, multi-touch touch-sensitive input devices can accurately recognize and capture multiple simultaneous touch contacts. For example, zooming in and out may be accomplished by placing two fingertips on a touchpad in positions separate from each other and moving the fingertips across the surface of the touchpad toward each other, and vice-versa.